Chevrolet 10 Series 1970, Service Manual

Page: 300 / 671

BRAKES 5-62
making sure the gro o ve in lock s le e v e is aligned with
pin in body. P r e s s shaft in until distance fro m sm all
end o f shaft to edge o f body (A , fig . 104) is 0.625".
In stall new welch plug in w orm shaft b ore.
4. P osition c o v e r p la tes on body and attach with new
riv e ts . C o v e rs must be fla t and in good contact with
body a fte r rivetin g.
Installation
1. If a new slack adjuster is being in stalled, make sure
it is the same s iz e and type as that rem oved. Make
sure spacing w asher is in place on cam shaft. Slide
the slack adju ster onto cam shaft and attach with
s p a cer and lock ring.
2. Connect brake cham ber push rod yoke to slack ad­
ju ster with c le v is pin and c o tter pin. R e fe r to
"B r a k e Cham ber In stallation ” fo r adjustment o f
brake cham ber push rod.
3. Adjust brakes as p revio u sly d irected under "B r a k e
A d ju stm en ts.”
Lubrication
Slack adju sters a re perm anently lu bricated by the man­
ufactu rer and req u ire no p e rio d ic lubrication. H ow ever,
i f a slack adju ster has been dism antled and rep a ired in
accordance with these p roced u res, it becom es n ecessa ry
to lu bricate upon rea ssem b ly.
1. Rem ove one plug fro m slack adjuster side plate.
2. Using a p re s s u re g rea se gun, in ject g re a s e into the
hole in side c o v e r while turning the worm shaft
approxim ately 50 revolu tions in one d irection .
3. In stall side plug secu rely.
4. Rotate w orm shaft three revolutions in the opposite
d irection .
5. R e fe r to Section 0 - Lubrication in this manual fo r
additional inform ation.
Slack Adjuster O p eratin g Test
Apply brakes and make sure a ll slack adjusters rotate
f r e e ly and without binding. R elea se brakes and make
sure a ll slack adjusters return to relea sed position fr e e ly
without binding.
With b rakes relea sed , make sure the angle fo rm ed by
slack adjuster arm and brake cham ber push rod is
g re a te r than 90 d eg rees. A ll slack adjusters should be
s et at the sam e angle. W ith brakes applied, make sure
the angle fo rm ed by the slack adjuster arm and brake
cham ber push rod is s till approxim ately 90 d e g re e s and
that a ll are at the sam e angle.
BRAKE SHOES A N D CAMSHAFTS
(Figs. 1 04, 1 05, 1 06, 1 0 7 )
Cam type brakes have an " S ” design cam on the end o f
the shaft that is operated by the brake diaphragm . The
cam op erates between the " f r e e ” end o f the brake shoes
and s e r v e s to expand the brake shoes against the drum.
Removal
Front
1. R em ove wheel nuts, rim locks and rim and tir e
assem bly.
2. R em ove c o tter pin, spindle nut, sp acer and outer
bearing.
3. Rem ove wheel and brake drum assem bly.
4. Rem ove brake shoe pull back springs.
5. Rem ove cam r o lle r s .
6. Rem ove " C ” w ashers, fla t w ashers and wave washers
fro m each hold down stud.
7. Rem ove brake shoe hold down nuts, w ashers and
anchor pin “ h orsesh oe” clip s.
8. Rem ove brake shoes.
9. Rem ove snap rin g fro m end o f cam shaft and rem ove
spacers.
10. Tap out cam shaft (fig . 105).
R ear
1. Rem ove wheel nuts, rim locks, and outer tir e and
rim assem bly.
2. Rem ove rim sp acer, then inner rim and tir e
assem bly.
3. Rem ove axle shaft retaining nuts and " s p lit w ed ge”
locks.
4. W ithdraw axle shaft.
5. Rem ove axle shaft lock nut, lock, and adjusting nut.
6. Rem ove wheel and brake drum assem bly, being
c a refu l not to damage outer bearing.
7. Slip shoe return spring o ff o f pins on inside o f brake
shoes. See F igu re 106 fo r parts identification.
8. R em ove c o tter pin fro m cam shaft and tap out cam ­
shaft.
9. Rem ove snap rings, spacer w ashers, anchor pins and
brake shoes.
C am shaft Bracket Bushing Replacem ent
1. Using a suitable tool rem ove grea se seal and old
bushings.
2. Using suitable bushing in sta lle r, in sta ll new bushing
and line ream to a finished d iam eter o f 1.499" to
1.501". Install a new g rea se seal.
NOTE: Be certain that a lubrication fittin g has
been installed in cam shaft bracket.
Installation
Front
1. Slide cam shaft into place making certa in brake shoes
w ill contact cam at p ro p er location.
F ig . 105—R emoving C am shaft (T y p ic a l)
CHEVROLET TRUCK SERVICE MANUAL